Television apparatus



May 30, 1939.

H. HARRIS 2,160,434 TELEVISION APPARAIU S Filed July. 18. 1936 I N V EN TOR. Kara r 149194 1.: B Y

A- ORNEYS.

Patented May 30, 1939 a A,

PATENT OFFICE TELEVISION APPARATUS Huston Harris, Corning, N. Y., assignor to Corning Glass Works, Corning, N. Y., a corporation of New York Application July 18, 1936, Serial No. 91,403

2 Claims.

Mly invention relates to improvements in television apparatus and the like, and particularly to the improvement of the optical fidelity of such apparatus.

In the past it has been common practice to manufacture envelopes for cathode ray tubes, used in television receivers to display images translated from picture signals received, by blowing the envelopes to the desired contour. The

shape of the envelope usually is that of a funnel, closed at the large end to form a screen upon which the images are displayed; and having the electrical elements constituting an electron gun for developing a cathode ray and for directing the same at the screen to produce images thereon, mounted in the stem. A similar practice has also been followed in the manufacture of the iconoscope tube which serves as a means for viewing scenes for television transmission and similar applications, and which is composed of an envelope containing an electron gun focused on a photosensitive signal plate Within the tube to develop picture signals in accordance with reflections received on the photosensitive signal plate of objects or scenes within View of a window comprising a part of the tube envelope structure.

In the blowing of a glass body it is impossible to obtain a perfect distribution and uniform thickness of glass in the wall, and while in ordinary vacuum tubes this may not be important, it is highly important in a cathode ray tube that the distribution, thickness and contour of the glass in that portion of the wall serving the screen be uniform, as otherwise distortion of the image produced thereon will result. For similar reasons it is important that the thickness and contour of the window of an iconoscope tube be uniform, as otherwise the object reflections on the signal plate will be distorted and fidelity of transmission and reproduction will be seriously impaired.

An object of the present invention is to transmit and reproduce pictures and views with fidelity.

Among its features my invention embodies a cathode ray tube envelope having a screen portion on which picture signals will be developed with perfect fidelity; also, an iconoscope tube envelope having a window therein through which light, reflected from objects or scenes within view of the window, will pass without distortion.

Other features embody the production of a vacuum tube envelope by sealing or welding a pre-formed optical screen or window portion of the envelope to a blown body portion thereof; the pre-formed body being produced in any well known manner, as by pressing, or by forming and subsequently grinding and polishing in accordance with the degree of perfection desired. 5

In the drawing:

Fig. 1 is a side view of a cathode ray tube having an envelope embodying this invention;

Fig. 2 is a side view, in section, of the blown and pressed parts of the envelope shown in Fig. 10 1 before they are sealed together;

Fig. 3 is a side view of an iconoscope tube having an envelope embodying this invention;

Fig. 4 is a view, similar to Fig. 2', of the parts of an iconoscope tube envelope embodying this invention; and

Fig. 5 is an end view of the intermediate part of the envelope shown in Fig. 4.

In the cathode ray tube the envelope is com.- posed of a blown glass body portion [0, the large end of which is carefully ground and sanded to free it of any metallic inclusions, and then welded or fused to a similarly prepared surface of a saucer-like pressed glass part II having a concaVo-convex screen or rounded area l2 in which the mass of glass is of uniform thickness and curvature throughout. If desired, the screen may be of plano-parallel configuration, but the concavo-convex configuration gives the exposed surface of the screen greater resistance to frac- 30 ture, and also corrects distortion caused by the changing curvature of the field with distance away from the cathode when a plano-parallel screen is used. An electron gun I3 of any known form is sealed in the neck of the envelope and is directed toward the screen area l2 in the usual 35 manner.

The iconoscope tube envelope comprises a main body in the form of a cylinder l6, the one end of which is ground, sanded and then welded or fused to a similarly prepared surface of a saucer-like part of pressed glass or the like having a plane-parallel screen or window area l8 within its wall areas l9 and 20. The lower wall area 20 has a protuberance 2| partly ground 011 at the point' indicated (Fig. 4) by the interrupted line H to form an apertured seat 22 to which a tubular part 23 of the envelope is welded at such an angle with respect to the axis of the cylinder it that an electron gun 24, sealed in the 5 remote end of tube 23, can scan the usual photo- 0 sensitive mosaic surfaced signal plate 25 to develop picture signals in accordance with light reflected from. objects or scenes within view of the window area [8.

disposed with respect to the line of juncture of the respective sections.

2. A glass envelope which includes two separately fabricated hollow parts one of which is adapted to transmit light generated within the 5 envelope, said parts being arranged in juxtaposed relation and fused together at their adjoining edges and the light transmitting part being so shaped that the larger portion thereof is in a plane remotely disposed with respect to the 10 line of juncture of the respective parts.

HUSTON HARRIS. 

